This hybridoma cell line was described as secreting a mouse monoclonal antibody (IgM) reacting with adult rat type 2B fibers in immunofluorescence and with rat type 2B MHCs (myosin heavy chain) in Western blotting; established in 1983 by fusion of NSO myeloma cells with spleen cells from a BALB/c mouse immunized with purified myosin from fetal bovine muscles